High RPM stumbling
06-09-2015, 12:11 PM
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High RPM stumbling
I have a b6 a4 (2002) 1.8 manual trans.
My problem is that my car stumbles badly at around 6k RPM. It smooths out at 6600 about intill fuel cutoff. Just replaced the crankshaft position sensor that was causing issues. The cel is on, but the only code is p0420 that keeps popping up (which says is cat below efficiency). I am going to check maf sensor and fuel filter. What other things should I look for?
My problem is that my car stumbles badly at around 6k RPM. It smooths out at 6600 about intill fuel cutoff. Just replaced the crankshaft position sensor that was causing issues. The cel is on, but the only code is p0420 that keeps popping up (which says is cat below efficiency). I am going to check maf sensor and fuel filter. What other things should I look for?
06-14-2015, 03:37 PM
#2
I would start by replacing spark plugs, air filter and the fuel filter, remove and clean the Maf & check the sensor. Also check the wiring inside the harness on the engine to the coils. A faulty coil should give you a code, but I have seen some worn wiring in the harness to the coils caused by age, grit, heat and moisture breaking down the insulation which could be a factor.
If you pull the Maf you may need to do an adaptation when you reinstall it. Some ECU's will do it automatically when you reconnect the MAF, turn ignition to on but not start, you can hear it doing the adaptation (full open, full closed etc) for about 20-30 seconds, but I have also had FSI engines that you need to instruct it via the VCDS.
If that doesn't fix it I would then start looking at fuel pressure and coils, I would have thought both would send some codes though.
If you pull the Maf you may need to do an adaptation when you reinstall it. Some ECU's will do it automatically when you reconnect the MAF, turn ignition to on but not start, you can hear it doing the adaptation (full open, full closed etc) for about 20-30 seconds, but I have also had FSI engines that you need to instruct it via the VCDS.
If that doesn't fix it I would then start looking at fuel pressure and coils, I would have thought both would send some codes though.
06-19-2015, 12:26 PM
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Awesome, thank you, I will defenetly try. I've done the fuel filter, now I'll start working on the other things. Thanks a ton. 
I would start by replacing spark plugs, air filter and the fuel filter, remove and clean the Maf & check the sensor. Also check the wiring inside the harness on the engine to the coils. A faulty coil should give you a code, but I have seen some worn wiring in the harness to the coils caused by age, grit, heat and moisture breaking down the insulation which could be a factor.
If you pull the Maf you may need to do an adaptation when you reinstall it. Some ECU's will do it automatically when you reconnect the MAF, turn ignition to on but not start, you can hear it doing the adaptation (full open, full closed etc) for about 20-30 seconds, but I have also had FSI engines that you need to instruct it via the VCDS.
If that doesn't fix it I would then start looking at fuel pressure and coils, I would have thought both would send some codes though.
If you pull the Maf you may need to do an adaptation when you reinstall it. Some ECU's will do it automatically when you reconnect the MAF, turn ignition to on but not start, you can hear it doing the adaptation (full open, full closed etc) for about 20-30 seconds, but I have also had FSI engines that you need to instruct it via the VCDS.
If that doesn't fix it I would then start looking at fuel pressure and coils, I would have thought both would send some codes though.
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